1. Field of the Invention
The invention relates to a device for pulling up the ends of continuously transverse-conveyed flat tubular segments during the production of sacks or bags. The inventive device comprises lateral support elements, which run parallel to the conveying zone and between which a slit is formed that lies in the conveying plane and beyond which the ends to be pulled up project, and the inventive device comprises mechanisms for pre-opening the ends by pulling apart the tubular sides that lie on top of each other.
2. Description of the Related Art
To produce the socalled block bottom bags, one end or both ends of a flat lying tubular segment is/are drawn up into socalled bottom squares. These bottom squares comprise socalled comer flaps made of isosceles triangles, whose base edges, which run parallel to each other, are spaced apart. The bottom squares are then sealed by folding so as to overlap and then by gluing the socalled side flaps while optionally inserting a socalled bottom slip and a valve tube.
From DE-AS 16 11 701, DE-PS 23 23 727 and DE-GM 82 34 461 it is known, for example, to pull up the ends of the tubular segments using suction mechanisms or also just to pre-open and then to smooth out the corner flaps of the bottom squares with rotating sickle-shaped spreading members. In so doing, there is the specific problem of adapting these rotating spreading members with such precision to the ends of the continuously conveyed tubular segments that said ends are spread out as smooth as possible without tears.